1. Field of the Invention
The present invention relates to a simplified locking structure of a wire rod for a filter element.
2. Description of the Prior Art
One of the locking structures of this kind is disclosed by the applicant in Japanese Patent Publication No. 16164/1988, and another in Japanese Patent Laid-open Application No. 9204/1988.
In the case of the former locking structure, one end portion of the wire rod, bent and wrapped around an insert member, is inserted in a recess formed on the circumferential surface of a cylindrical body, and securely locked by means of a locking bolt, which is inserted through a hole formed on the opposed walls of the insert member and the recess, and is engaged in a threaded portion formed in the bottom of the hole.
The above-described prior art structures are advantageous for filter elements of high precision filtering material made through precision finishing method.
In the latter locking structure, the locking structure is largely simplified by utilizing a wedge instead of the insert member and also the locking bolt of the former case, and thereby the end portion of the wire rod being pushed by the wedge and secured within a locking hole.
The aforementioned prior art patents, which were disclosed by the same applicant of the present invention, are provided with certain advantages and effects according to the improved locking structure, accuracy or dimension of the filter element.
There are still some problems that an insert member or a wedge is necessary as a locking member. In particular, in the case when an inexpensive filter element can be provided by using cheaper materials such as plastics, the locking structure should be further simplified to expedite mass production.